diff --git a/com.avaloq.tools.ddk.check.ui.test/META-INF/MANIFEST.MF b/com.avaloq.tools.ddk.check.ui.test/META-INF/MANIFEST.MF
index c475c69de2..bf21036e77 100644
--- a/com.avaloq.tools.ddk.check.ui.test/META-INF/MANIFEST.MF
+++ b/com.avaloq.tools.ddk.check.ui.test/META-INF/MANIFEST.MF
@@ -29,8 +29,7 @@ Require-Bundle: com.avaloq.tools.ddk.check.ui,
 Export-Package: com.avaloq.tools.ddk.check.ui.test,
  com.avaloq.tools.ddk.check.ui.test.util,
  com.avaloq.tools.ddk.check
-Import-Package: org.slf4j,
- org.hamcrest.core,
+Import-Package: org.hamcrest.core,
  org.junit.runner;version="4.5.0",
  org.junit.runner.manipulation;version="4.5.0",
  org.junit.runner.notification;version="4.5.0",
diff --git a/com.avaloq.tools.ddk.xtext.test.core/META-INF/MANIFEST.MF b/com.avaloq.tools.ddk.xtext.test.core/META-INF/MANIFEST.MF
index 47dd4106a2..820ccc4b2e 100644
--- a/com.avaloq.tools.ddk.xtext.test.core/META-INF/MANIFEST.MF
+++ b/com.avaloq.tools.ddk.xtext.test.core/META-INF/MANIFEST.MF
@@ -26,7 +26,7 @@ Require-Bundle: com.avaloq.tools.ddk.xtext,
  org.eclipse.emf.common,
  com.avaloq.tools.ddk,
  junit-jupiter-api
-Import-Package: org.slf4j, org.apache.logging.log4j
+Import-Package: org.apache.logging.log4j
 Export-Package: com.avaloq.tools.ddk.xtext.test,
  com.avaloq.tools.ddk.xtext.test.contentassist,
  com.avaloq.tools.ddk.xtext.test.conversion,
diff --git a/com.avaloq.tools.ddk.xtext.test/META-INF/MANIFEST.MF b/com.avaloq.tools.ddk.xtext.test/META-INF/MANIFEST.MF
index 9da79bec67..0fe705076a 100644
--- a/com.avaloq.tools.ddk.xtext.test/META-INF/MANIFEST.MF
+++ b/com.avaloq.tools.ddk.xtext.test/META-INF/MANIFEST.MF
@@ -45,8 +45,7 @@ Import-Package: com.avaloq.tools.ddk.check.runtime.test.core,
  com.avaloq.tools.ddk.xtext.test.export,
  com.avaloq.tools.ddk.xtext.test.format,
  com.avaloq.tools.ddk.xtext.ui.test,
- org.apache.logging.log4j,
- org.slf4j
+ org.apache.logging.log4j
 Export-Package: com.avaloq.tools.ddk.xtext,
  com.avaloq.tools.ddk.xtext.formatter,
  com.avaloq.tools.ddk.xtext.formatter.services,
diff --git a/com.avaloq.tools.ddk.xtext.test/pom.xml b/com.avaloq.tools.ddk.xtext.test/pom.xml
index 4a30dfc6a2..c7ac764fb1 100644
--- a/com.avaloq.tools.ddk.xtext.test/pom.xml
+++ b/com.avaloq.tools.ddk.xtext.test/pom.xml
@@ -24,7 +24,7 @@
           <useUIThread>false</useUIThread>
           <useUIHarness>true</useUIHarness>
           <forkedProcessTimeoutInSeconds>${test.timeout}</forkedProcessTimeoutInSeconds>
-          <argLine>-Dlogback.configurationFile="${runtime.logbackConfig}" ${test.javaOptions}</argLine>
+          <argLine>-Dslf4j.internal.verbosity=ERROR -Dlogback.configurationFile="${runtime.logbackConfig}" ${test.javaOptions}</argLine>
           <appArgLine>-pluginCustomization ${runtime.pluginCustomization}</appArgLine>
           <product>${runtime.product}</product>
           <application>org.eclipse.ui.ide.workbench</application>